Thank you Nathan, i too think it's something linked to collision detection... The situation i am modeling is: There's an EMP grenade with a certain effect range. And there are some silicon wafers with a certain shape. Now when the grenade explode it will trigger some effects on any wafer that have any amount of surface affected.
Doing the standard CollDect that you suggested seem to me a little too inefficient, i am wondering if exist some way to say to a crowd of objects "hey anyone that have a toe in this area should do this" without checking for each one of them